1. Field of Invention
An improved and controlled natural antioxidant and/or flavor composition from rosemary and other Labiatae.
2. State of the Art
It has been known for years that members of the family Labiatae, the mint family, comprising such well-known herbs as sage, rosemary, thyme, peppermint, etc., contain substances which retard the fading of paprika and other natural colors, reduce the rate at which pork fat, and more particularly port sausage, goes rancid, and which inhibit the oxidation of fats in poultry, other meats, and baked goods, among other food items.
The use of spices, herbs, and various forms thereof for such purposes is not new to the art. Maveety (U.S. Pat. No. 2,124,706 disclosed this concept in 1938. Crude extracts of these herbs or the herbs themselves were used to achieve the intended effect. There was no ready, practical method of measuring the activity of the herb or the extract, particularly in relation to its flavor, and the use was limited.
More recently, various techniques have been developed to provide a less-flavorful extract, in both liquid and powder form. The powder form (Kimura U.S. Pat. No. 4,363,823) is made by extracting a fresh or previously steam-distilled herbal residue with, for example, alcohol, and evaporating the alcohol to form a pasty substance. Alternatively, the desolventized extract may be added to boiling water, which will dissolve the extracted water solubles and leave the insolubles, including the antioxidants, as a precipitate which can be filtered, dried, and powdered. If the precipitate is well washed with water, hygroscopic materials are removed and the resulting dried powder, containing some flavor, antioxidants, and fats and waxes, will not become hard in the presence of moist air. Non-polar solvents are not of choice, because drying of the spent herbal residue is required.
Viani (U.S. Pat. No. 4,012,531) shows the direct extraction of dried herbal materials (rosemary and sage) with an aqueous basic solution, at a pH between about 7 and 11.5 and preferably about 9, to remove the antioxidant materials from the herbal substrate. Viani points out (Col 2, line 23) that this upper limit on pH is critical, since it prevents the removal of strongly acidic, pro-oxidant substances from the rosemary. The alkaline extract may be used as such, dried, or extracted into a water-immiscible solvent such as methylene chloride following acidification. Viani's extract has a very slight rosemary odor (Example 1, Col 5, line 57).
Nakatani (U.S. Pat. No. 4,450,097) varies this procedure by first extracting the dried herb with a non-polar organic solvent such as hexane, removing the hexane, steam distilling off the volatile essential oils from an aqueous dispersion, cooling, and separating the water-insoluble rosemary extract. This deodorized extract is then dissolved in ether, acid washed, and then the ether solution is extracted with sodium bicarbonate at a pH of at least 10.5. Apparently, using bicarbonate, the weakly acidic, prooxidant fraction described by Viani is not extracted from the ether into the water. Nakatani also shows that rosemary leaves may first be steam distilled to remove the essential oils, and then extracted with a non-polar solvent and the extract refined as above. (It should be emphasized that the purified extract of the present invention greatly simplifies the processes mentioned above, since it reduces emulsions and particulate matter, and simplifies the pH separations.)
Berner (U.S. Pat. No. 3,732,111) uses an edible fat to extract the dried herb, removes the essential oil from the extract dissolved in fat, and then utilizes this deodorized extract in fat as an antioxidant. This process has the distinct disadvantage of wasting a substantial amount of edible fat in the spent herb, and in being unable to concentrate the extract.
Chang (U.S. Pat. No. 3,950,266) extracted dried rosemary leaves with organic solvent, removed the solvent, mixed the extract with a high-boiling or non-volatile edible oil such as soy oil, and steam distilled the resulting mixture to remove the flavor of rosemary, leaving behind the flavorless antioxidant fraction. He also molecularly distilled the fluid, before or after decolorizing with charcoal, to obtain a concentrated antioxidant. In addition, Chang showed that contacting the extract with solvents of greater and lesser polarity concentrated the antioxidant fraction in the solvent of greater polarity using column chromatography. Chang has the distinct advantage over Berner in providing a concentrated antioxidant which can be used in many applications in which the fat used by Berner would be objectionable.
Bracco (U.S. Pat. No. 4,352,746) utilized the discoveries of both Chang and Berner to provide a method applicable to both fat and solvent extracts of herbs. This procedure is also applicable to both steam-distilled rosemary leaves and rosemary containing the essential oil. In Bracco's invention, the extract in oil, or the solvent extract, after desolventization and suspension in oil, is micronized, and then carbonized in the presence of water by heat treatment. The carbonized suspension is sieved to remove the carbonized material, and the fluid fraction is then molecularly distilled to obtain a concentrated antioxidant fraction in the manner of Chang. However, Bracco finds that his invention allows him to use less oil than Chang, in relation to the herb. Thus, his oil may contain 5 to 20% equivalents of the vegetable starting material, as opposed to 1 to 2% for Chang's process (Col. 4, line 65). Presumably this improvement is due to the carbonization step, which removes materials which will clog the molecular distillation apparatus.
In a more recent patent, Kimura (U.S. Pat. No. 4,380,506) describes a process for the separation of an oil-soluble and an oil-insoluble (Example 3) active fraction from the herbal extract. He used ethanol-hexane mixtures ranging from 2% ethanol to 95% ethanol in hexane to extract sage, and showed that all of these mixtures were very effective extraction solvents. By adding the extract, dissolved in the extraction solvent mixture, to water he was able to separate the rosemary extract into a hexane-soluble portion and a hexane-insoluble portion. The hexane-soluble portion was also oil soluble, and had strong antioxidant activity. The precipitate formed, when the extract dissolved in solvent was added to water, was oil-insoluble, weakly antioxidant (perhaps as a result of entrained hexane-soluble materials), but useful as an anti-bacterial perservative. This precipitate is not the acetone-insoluble material according to the present invention, which does not have antibacterial properties. Kimura shares the disadvantage of Berner in losing solvent (ethanol) to the admixed water phase, and also has the disadvantage over this invention of using an amount of solvent which is ten times the weight of his spice for purifying the extract (Examples 1 and 2), which would effectively dissolve the "acetone-insoluble" materials into the hexane phase, which acetone-insoluble materials are eliminated by this invention. Kimura never eliminates the acetone-insoluble impurities from his hexane phase or otherwise.